"""
    This module provides more sophisticated flow tracking. These match requests
    with their responses, and provide filtering and interception facilities.
"""
import subprocess, base64, sys, json
import proxy, threading, netstring
import controller

class RunException(Exception):
    def __init__(self, msg, returncode, errout):
        Exception.__init__(self, msg)
        self.returncode = returncode
        self.errout = errout


# begin nocover
class ReplayThread(threading.Thread):
    def __init__(self, flow, masterq):
        self.flow, self.masterq = flow, masterq
        threading.Thread.__init__(self)

    def run(self):
        try:
            server = proxy.ServerConnection(self.flow.request)
            server.send_request(self.flow.request)
            response = server.read_response()
            response.send(self.masterq)
        except proxy.ProxyError, v:
            err = proxy.Error(self.flow.client_conn, v.msg)
            err.send(self.masterq)
# end nocover


class Flow:
    def __init__(self, client_conn):
        self.client_conn = client_conn
        self.request, self.response, self.error = None, None, None
        self.intercepting = False
        self._backup = None

    def script_serialize(self):
        data = self.get_state()
        return json.dumps(data)

    @classmethod
    def script_deserialize(klass, data):
        try:
            data = json.loads(data)
        except Exception:
            return None
        return klass.from_state(data)

    def run_script(self, path):
        """
            Run a script on a flow.

            Returns a (flow, stderr output) tuple, or raises RunException if
            there's an error.
        """
        self.backup()
        data = self.script_serialize()
        try:
            p = subprocess.Popen(
                    [path],
                    stdout=subprocess.PIPE,
                    stdin=subprocess.PIPE,
                    stderr=subprocess.PIPE,
                )
        except OSError, e:
            raise RunException(e.args[1], None, None)
        so, se = p.communicate(data)
        if p.returncode:
            raise RunException(
                "Script returned error code %s"%p.returncode,
                p.returncode,
                se
            )
        f = Flow.script_deserialize(so)
        if not f:
            raise RunException(
                    "Invalid response from script.",
                    p.returncode,
                    se
                )
        self.load_state(f.get_state())
        return se

    def get_state(self, nobackup=False):
        d = dict(
            request = self.request.get_state() if self.request else None,
            response = self.response.get_state() if self.response else None,
            error = self.error.get_state() if self.error else None,
            client_conn = self.client_conn.get_state()
        )
        if nobackup:
            d["backup"] = None
        else:
            d["backup"] = self._backup
        return d

    def load_state(self, state):
        self.client_conn = proxy.ClientConnection.from_state(state["client_conn"])
        self._backup = state["backup"]
        if state["request"]:
            self.request = proxy.Request.from_state(self.client_conn, state["request"])
        if state["response"]:
            self.response = proxy.Response.from_state(self.request, state["response"])
        if state["error"]:
            self.error = proxy.Error.from_state(state["error"])

    @classmethod
    def from_state(klass, state):
        f = klass(None)
        f.load_state(state)
        return f

    def __eq__(self, other):
        return self.get_state() == other.get_state()

    def modified(self):
        # FIXME: Save a serialization in backup, compare current with
        # backup to detect if flow has _really_ been modified.
        if self._backup:
            return True
        else:
            return False

    def backup(self):
        self._backup = self.get_state(nobackup=True)

    def revert(self):
        if self._backup:
            self.load_state(self._backup)
            self._backup = None

    def match(self, pattern):
        if pattern:
            if self.response:
                return pattern(self.response)
            elif self.request:
                return pattern(self.request)
        return False

    def is_replay(self):
        return self.client_conn.is_replay()

    def kill(self):
        if self.request and not self.request.acked:
            self.request.ack(None)
        elif self.response and not self.response.acked:
            self.response.ack(None)
        self.intercepting = False

    def intercept(self):
        self.intercepting = True

    def accept_intercept(self):
        if self.request:
            if not self.request.acked:
                self.request.ack()
            elif self.response and not self.response.acked:
                self.response.ack()
            self.intercepting = False


class State:
    def __init__(self):
        self.flow_map = {}
        self.flow_list = []
        # These are compiled filt expressions:
        self.limit = None
        self.intercept = None

    def add_browserconnect(self, f):
        """
            Start a browser connection.
        """
        self.flow_list.insert(0, f)
        self.flow_map[f.client_conn] = f

    def add_request(self, req):
        """
            Add a request to the state. Returns the matching flow.
        """
        f = self.flow_map.get(req.client_conn)
        if not f:
            f = Flow(req.client_conn)
            self.add_browserconnect(f)
        f.request = req
        return f

    def add_response(self, resp):
        """
            Add a response to the state. Returns the matching flow.
        """
        f = self.flow_map.get(resp.request.client_conn)
        if not f:
            return False
        f.response = resp
        return f

    def add_error(self, err):
        """
            Add an error response to the state. Returns the matching flow, or
            None if there isn't one.
        """
        f = self.flow_map.get(err.client_conn)
        if not f:
            return None
        f.error = err
        return f

    def load_flows(self, flows):
        self.flow_list.extend(flows)
        for i in flows:
            self.flow_map[i.client_conn] = i

    def set_limit(self, limit):
        """
            Limit is a compiled filter expression, or None.
        """
        self.limit = limit

    @property
    def view(self):
        if self.limit:
            return tuple([i for i in self.flow_list if i.match(self.limit)])
        else:
            return tuple(self.flow_list[:])

    def get_client_conn(self, itm):
        if isinstance(itm, proxy.ClientConnection):
            return itm
        elif hasattr(itm, "client_conn"):
            return itm.client_conn
        elif hasattr(itm, "request"):
            return itm.request.client_conn

    def lookup(self, itm):
        """
            Checks for matching client_conn, using a Flow, Replay Connection,
            ClientConnection, Request, Response or Error object. Returns None
            if not found.
        """
        client_conn = self.get_client_conn(itm)
        return self.flow_map.get(client_conn)

    def delete_flow(self, f):
        if not f.intercepting:
            c = self.get_client_conn(f)
            if c in self.flow_map:
                del self.flow_map[c]
            self.flow_list.remove(f)
            return True
        return False

    def clear(self):
        for i in self.flow_list[:]:
            self.delete_flow(i)

    def accept_all(self):
        for i in self.flow_list[:]:
            i.accept_intercept()

    def kill_flow(self, f):
        f.kill()
        self.delete_flow(f)

    def revert(self, f):
        conn = self.get_client_conn(f)
        f.revert()

    def replay(self, f, masterq):
        """
            Returns None if successful, or error message if not.
        """
        #begin nocover
        if f.intercepting:
            return "Can't replay while intercepting..."
        if f.request:
            f.backup()
            conn = self.get_client_conn(f)
            f.client_conn.set_replay()
            if f.request.content:
                f.request.headers["content-length"] = [str(len(f.request.content))]
            f.response = None
            f.error = None
            rt = ReplayThread(f, masterq)
            rt.start()
        #end nocover


class FlowMaster(controller.Master):
    def __init__(self, server, state):
        controller.Master.__init__(self, server)
        self.state = state

    # Handlers
    def handle_clientconnection(self, r):
        f = Flow(r)
        self.state.add_browserconnect(f)
        r.ack()
        return f

    def handle_error(self, r):
        f = self.state.add_error(r)
        if not f:
            r.ack()
        return f

    def handle_request(self, r):
        f = self.state.add_request(r)
        if not f:
            r.ack()
        return f

    def handle_response(self, r):
        f = self.state.add_response(r)
        if not f:
            r.ack()
        return f


class FlowWriter:
    def __init__(self, fo):
        self.fo = fo
        self.ns = netstring.FileEncoder(fo)

    def add(self, flow):
        d = flow.get_state()
        s = json.dumps(d)
        self.ns.write(s)


class FlowReader:
    def __init__(self, fo):
        self.fo = fo
        self.ns = netstring.decode_file(fo)

    def stream(self):
        """
            Yields Flow objects from the dump.
        """
        for i in self.ns:
            data = json.loads(i)
            yield Flow.from_state(data)